I knew of people in college that were socially inept probably because they spent much of their time in isolation working on computer hobbies growing up. I'd see them in the labs and they always seemed really depressed. It seemed like they lamentee not having friends being invited places, etc... I get it because when I moved to a new city I felt like I had that same problem except only temporarily. But living your life with minimal human contact with others? I'd regret that.

You have an imagination right? It's actually worse because your regretting not doing a thing that is only in your imagination which is impossible to live up to. So you're sad because you didn't do x, let's say snoboarding bit since you haven't done it you are regretting imagination not regretting not doing more of something you understand well.